As described in U.S. Pat. No. 8,282,453 to CNH America LLC, which is incorporated by reference herein in its entirety, a combine harvester is a machine that is used to gather, thresh, and clean a wide range of grain crops while returning the straw, chaff and material other than grain (MOG) back to the earth in a single pass over the field. Typically, a combine harvester gathers the crop from the field with a header and transports the crop by means of a feeder house to a threshing and separating device located inside the combine. Generally, threshing refers to removing grain, beans, seeds or kernels, hereinafter referred to as just grain, which are desired to be collected, from husks, cobs, pods, stems, straw, and other portions of the plants being harvested, which are to be discarded.
Referring now to the prior art figures, FIG. 1 shows an agricultural combine 10 according to the prior art. The combine 10 includes a longitudinally axially arranged threshing and separation system 14 of well-known construction and operation.
As shown, threshing and separation system 14 is axially arranged, in that it includes a cylindrical threshing rotor 12 conventionally supported and rotatable in a predetermined direction about a rotational axis there through for conveying a flow of crop material in a helical flow path through a threshing chamber 16 extending circumferentially around the rotor 12. As shown, concaves 18 extend circumferentially around the rotor 12 and the flew of crop passes in the space between the spinning rotor and the concaves. As the crop material flows through the threshing and separation system 14, the crop material including, for example, gram, straw, legumes, and the like, will be loosened and separated from crop residue or waste such as, for example, husks, cobs, pods, and the like, and the separated materials may be carried away from the threshing and separation system 14 in a well-known conventional manner. As threshed crop falls through the grates in concaves 8 and other grates, it is moved by a conveyor system to a grain bed in a cleaning system, as is described hereinafter.
FIG. 2 shows a more detailed figure of grain movement from thresher rotor 12 to the auger bed 70 and then to the grain bed 22 of the cleaning system 20. The threshed crop follow paths 102. Grain and MOG falling through the grates in the concave area 18, lands on the auger bed 70 or a grain pan 76. Grain pan 76 is used in conjunction with a sloping overhead return pan 84 that prevents falling threshed crop from directly impacting the grain bed 22 in cleaning system 20.
The auger bed 70 comprises a series of parallel augers 72 that are each positioned in a separate trough 73. Five parallel augers 72 oriented from the front to back of the combine rotate in parallel troughs 73 to move grain and MOG onto grain pan 76. After passing grain pan 76, threshed crop is moved on to grain bed 22. Once on the grain bed 22, the upper sieve 26 reciprocates to move crop material backwards along the length of the grain bed 22 in direction 100 to separate out the grain. The heavy crop matter instead exits the rear of the grain bed in direction 106.
Additional conveyance capacity of the auger bed 70 is sought as the capacity of modern harvesters increase. However, the processing capacity of the auger bed 70 is finite. Simply increasing the rotating speed of the auger can damage the grain and can also have negative effects on cleaning system performance. It is not possible to simply increase the width of the auger bed 70 or the diameter of the augers 72 within the bed 70 due to vehicle size constraints and without affecting the position of other functional components of the harvester.
What is sought is a way to increase conveyance capacity of an auger bed without increasing the rotating speed of the augers or increasing the width or ceiling height of the auger bed.